This study is designed to test the hypothesis that daily treatment of diabetic foot ulcers with an enzymatic debriding agent, SANTYL, for up to 6 weeks will result in more rapid decrease in ulcer area than diabetic foot ulcers treated with a topical treatment containing silver. After meeting study criteria, participants will be randomly assigned to apply Santyl or a topical treatment containing silver to their to foot ulcer for up to 6 weeks. At the end of 6 weeks, participants will be followed for an additional 4 weeks to examine the outcome of the study treatment.